The study of peripheral arterial disease in the diabetic has been initiated. The following baseline measurements have been collected: systolic blood pressure in the upper and lower extremities with transcutaneous Doppler techniques at rest and after exercise; measurement of pulse volume of the extremities by segmental plethysmography and Doppler examination of the arteries; fasting plasma glucose; serum cholesterol and triglycerides; quantitative lipoproteins; platelet factor 4; circulating platelet aggregates; platelet aggregation studies; ristocetin Willebrand factor and Willebrand antigen. Clincial data have been abstracted on all subjects recruited. These clincial data include age, sex, height, weight, pertinent history and physical findings and previous laboratory data. A total of 707 subjects have been enrolled and the aforementioned studies completed on all of them: 124 normal control subjects, 158 subjects with occlusive arterial disease of the lower extremities without diabetes; 300 diabetic patients without clinical occlusive arterial disease of the lower extremities and 125 patients with clinical occlusive arterial disease of the lower extremities. Platelet survival studies have been completed on 78 patients: 21 normal control subjects, 13 patients with occlusive arterial disease of the lower extremities without diabetes and 44 diabetic patients with and without occlusive arterial disease of the lower extremities. The clinical and laboratory data have been collected, edited, corrected and entered into the master file for initial descriptive analysis and future comparison analysis of variables. The collection of baseline data is the first step in the evaluation of arterial, plasma and platelet changes over time and this collection has been accomplished. This study will provide data as to the natural history of the progression of vascula disease in diabetic patients and whether these changes can be correlated with plasma glucose, serum lipids and, more importantly, platelet and plasma coagulation factors. The possible correlation of vascular changes with platelet and plasma factors is an important consideration in the arteriosclerotic disease of diabetic patients. If such a correlation exists, it may provide a mechanism for the development of atherosclerotic lesions in the diabetic and may point, to the need for new modes of therapy.